We propose to study the genetic regulation of alcohol metabolism in the yeast, saccharomyces cerevisiae. In particular, we will investigate the regulation of the genes coding for the two cytoplasmic isozymes of alcohol dehydrogenase (ADH). Mutants defective in repression and derepression of isozyme ADH II, a glucose-repressible enzyme, will be isolated and characterized. Immunological assays for the constitutive and repressible ADH isozymes will be developed and then used to quantitate the level of ADH protein in repressed and derepressed cells. The immunological assay will also be used in conjunction with cell-free protein synthesis to measure ADH mRNA in repressed and derepressed cells. Using purified ADH mRNA we will clone the ADH genes in bacterial plasmids or phage lambda. The cloned ADH genes will then be used to detect nuclear and cytoplasmic ADH RNA, and to determine the location and sequence of genetic regulatory sites near the ADH II gene.